In non-invasive imaging systems, X-ray tubes are used in various X-ray systems and computed tomography (CT) systems as a source of X-ray radiation. Typically, an X-ray tube includes a cathode and an anode. An emitter within the cathode may emit a stream of electrons in response to heat resulting from an applied electrical current. The electron stream may be guided toward the anode by one or more electrical or magnetic fields positioned along the electron stream. The anode generally includes a target that is impacted by the stream of electrons. The target may, as a result of impact by the electron beam, produce X-ray radiation that is emitted from the X-ray tube.
In typical imaging applications, the radiation passes through a subject of interest, such as a patient, baggage, or an article of manufacture, and a portion of the radiation impacts a detector or photographic plate where the image data is collected. The detector produces signals representative of an amount or intensity of radiation impacting discrete elements of the detector. The signals may then be processed to generate an image that may be displayed for review. In CT systems, a detector array, including a series of detector elements, produces similar signals through various positions as a gantry is rotated about a patient. In other systems, such as systems for oncological radiation treatment, the X-ray tube may produce ionizing radiation directed toward a target tissue.
The cathode of an X-ray tube may include one or more emitters having various configurations. However, as emitters are generally becoming larger, the first resonant frequency is being driven lower and lower. This modal frequency eventually arrives within the range of other structurally relevant frequencies of the X-ray tube, such as the anode rotor operational frequency. When this modal frequency exists at, or below the other operational frequencies of the X-ray tube, energy may be deposited into this mode, introducing emitter deformation and encouraging additional failure modes. Furthermore, the larger emitters may have less structural rigidity resulting in challenges during fabrication, assembly, shipment, and operation. In addition, multiple emitters may be used, compounding placement accuracy problems, in particular when placing them in close proximity to each other or any external geometry.
It would be advantageous to provide methods for fabrication and stiffening that overcome these and other disadvantages.